RU2656004C1 - Method for determining the topology of overhead power transmission lines - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: invention relates to electrical measuring equipment and can be used to determine the topology of overhead power transmission lines (PTLs), that is, to determine the presence of branches, distances to attachments, and the lengths of branches. Essence: sounding pulses are sent to the line. Pulses reflected from the inhomogeneities enter the receiving-regulating device, then the measuring device for analyzing the trace. Using the initial section of the trace, the value of the repetition frequency of the reflected pulses, corresponding to inhomogeneities of the unbranched line, is determined. Presence of the branch is determined by the stepwise increase in the repetition frequency of the reflected pulses on the trace. Attachment point of the branch is specified by the presence of a negative polarity pulse on the trace. End point of the branch is determined by the stepwise decrease in the repetition frequency of the reflected pulses. Length of the branch is determined by the specified attachment point and the end point of the branch.

EFFECT: expansion of functional capabilities.

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Description

The invention relates to electrical engineering and can be used to determine the topology of overhead power lines (power lines), that is, to determine the presence of branches, distances to connections, branch lengths.

The known method of OMP (AS No. 2319972 C1 dated 03/20/2008 "Method for determining the presence of defects in wires and cables in network segments with a branched topology"), which consists in the fact that the leading terminal equipment simultaneously performs location-based sensing and measurement of the carrier phase, adopted from the slave terminal equipment, the data are recorded in the memory of the microcomputer, the measured phase value and the shape of the trace are compared with the previous values, and in the event of a change in the phase value or shape of the trace, the presence or absence of resulting damage to probed segment.

The disadvantages of this method are: the requirement for accurate synchronization of the slaves with the master when measuring the phase of the carrier; the need for their constant combination of time keepers; the difficulty of measuring the phase of the signal with the necessary accuracy due to the high level of interference in power transmission networks. In addition, the method allows you to determine damage in specific segments, while the overall network topology is not determined.

A known method for determining the location of damage in networks with a branched topology (application No. 2008151219/28 dated 12/23/2008), including scanning the network in sections using slaves and sequential location-based sensing of damaged segments obtained on the basis of scan data. The main disadvantage of this method is that to determine the network topology, it is necessary to install slave devices along the entire power transmission line, which ultimately increases the cost and complicates the implementation of this method.

The closest in technical essence to the proposed invention (prototype) is the method (Shalyt G.M. Determination of damage points in electric networks. - M: Energoizdat, 1982, p. 188), which is as follows. Sensing pulses are fed into the line. Reflecting from the places of damage and inhomogeneities, the pulses enter the receiving and regulating device, then to the measuring device for analyzing the reflectogram. The time interval between the probe pulse and the pulse reflected from the damage site is fixed. This time interval is proportional to the distance from the beginning of the line to the place of damage. This method gives mixed results in determining the damage sites of branched power lines, and also does not allow to determine the topology of power lines.

The objective of the proposed technical solution is to expand the functionality, which consists in determining the topology of power lines. The method allows to determine the presence of branches, the distance to the connections, the length of the branches.

For this, in the proposed method, probing pulses are fed into the line. Reflecting from inhomogeneities, the pulses enter the receiving and regulating device, and then to the measuring device for analyzing the reflectogram. Unlike the prototype, trace analysis is performed as follows. The pulse repetition rate is analyzed. Using the initial portion of the trace, the value of the reflected pulse repetition rate corresponding to the inhomogeneities of the unbranched line is determined. The presence of a branch is determined by an abrupt increase in the repetition rate of reflected pulses. The connection point of the branch is determined by the presence of a pulse of negative polarity on the trace. The location of the branch end is determined by an abrupt decrease in the repetition rate of the reflected pulses. The length of the branch is determined by the specified place of accession and the location of the end of the branch.

In FIG. 1 shows an example of the topology of a power line with one branch;

in FIG. 2 shows a reflectogram corresponding to this example of a power line;

in FIG. 3 shows an example of a power line with several branches;

in FIG. 4 shows a trace corresponding to the power transmission line shown in FIG. 3.

Consider the proposed method in the following example. In overhead power transmission lines, supports are located at approximately equal distances. Due to a sharp change in the geometry of the lines in the places of supports and the presence of wire fastening elements, changes in the wave impedance of the line appear. Modern reflectometry tools can reliably detect such heterogeneities.

When a probe pulse is sent to the line in the places of inhomogeneities, reflected pulses of small amplitude arise. The reflected pulse repetition rate depends on the distance between the supports. If the power transmission line does not have branches, then the repetition rate of the reflected pulses along the trace is inversely proportional to the distance between the inhomogeneities of the wave resistance.

If the power transmission line has branches, then the reflected pulses will also occur in the branches. As a result, pulses having a high repetition rate will be present at a certain portion of the trace. Consider a power line with one branch (Fig. 1). After sending a probe pulse from point A, reflected pulses will first appear, corresponding to the inhomogeneities of section AB with a repetition rate of ƒ ₁ (Fig. 2). In the BB section, there will be pulses with a repetition rate of соответствующие ₂ corresponding to the inhomogeneities of the BB branch and the inhomogeneities of the BB segment.

If the distances between the inhomogeneities in the BB section are the same as in the BB region, then the reflected pulse repetition rate will be twice as high as the frequency ƒ ₁ . In real reflectograms, the frequency ƒ _{2 is} always significantly higher than the frequency ƒ ₁ .

At the end of the reflected pulses with a repetition rate ƒ _{2 of the} BB section (Fig. 2), reflected pulses will appear corresponding to the section VG with the repetition frequency of ƒ ₃ . The frequency ƒ ₃ will be equal to the frequency ƒ ₁ , and on a real trace, it will be close to the frequency ƒ ₁ .

Consider the case when the power line has several branches (Fig. 3). At section A-B waveform (FIG. 4) of the reflected pulse repetition frequency is ƒ _1, the area B-G reflected pulse repetition frequency is ƒ _2, ƒ ₂ wherein> ƒ ₁ have been started branch B-B. The beginning of the branch corresponds to a negative impulse at point B. In the G-B section there are reflected pulses corresponding to the main line and two branches. The repetition rate of these reflected pulses is ƒ ₃ , and ƒ ₃ > ƒ ₂ , since the G – B section of the GE branch has begun. The beginning of the branch corresponds to a negative pulse at point G. In the V – D section of the reflectogram (Fig. 4), the frequency the succession of the reflected pulses is ƒ ₄ , and ƒ ₄ <ƒ ₃ , since the B-B branch has ended. These pulses correspond to the section B'-D 'of the main line and the section B "-D of the branch GE. In the D-E plot of the trace, the repetition rate of the reflected pulses is ƒ ₅ , and ƒ ₅ > ƒ ₄ , since the D-J branch has begun. The beginning of the branch corresponds to a negative impulse at point D of the trace. In the E – F section of the trace, the reflected pulse repetition rate will be ƒ ₆ , and ƒ ₆ <ƒ ₅ , since the GE branch has ended. In the section Z-Z of the reflectogram, the repetition rate of the reflected pulses will be equal to ƒ ₇ , and ƒ ₇ <, ₆ , since the branch J has ended. The frequency ƒ ₇ will be equal to the frequency ƒ ₁ , and on a real trace, it will be close to the frequency ƒ ₁ .

In the general case, the presence of a branch is determined by the presence on the trace of a section with an increased repetition rate of reflected pulses.

At the point of attachment of the branch, the wave impedance decreases, which leads to the appearance of a reflected pulse of negative polarity. The connection point is determined by the presence of a negative pulse, after which the reflected pulses begin with an increased repetition rate, using the formula

- расстояние до присоединения;Where

- distance to accession;

V is the propagation velocity of electromagnetic waves in the test line;

τ ₃ - delay time reflected from the point of attachment of the pulse branch relative to the probe.

определяется по формулеThe branch length, for example, on the power lines of FIG. 1 is determined by two points of the trace of FIG. 2: the first point t _1, which corresponds to a pulse of negative polarity and a second point t ₂ after which the reflected pulse repetition rate abruptly decreases. Branch length

determined by the formula

Thus, the technical result consists in the fact that using the trace obtained from one end of the power transmission line, it becomes possible to determine the topology of the power transmission line.

The method can be used to determine the integrity of the wires of power lines after accidents to detect unauthorized connections, and also as part of the method of determining the location of damage in power lines with a branched topology.

Claims (1)

A method for determining the topology of overhead power lines, in which probing pulses are fed into the line, pulses reflected from inhomogeneities are fed to a receiving and regulating device, then to a measuring device for analyzing the received reflectogram, characterized in that, using the initial portion of the reflectogram, the reflected pulse repetition rate is determined corresponding to the inhomogeneities of the unbranched line, then the presence of a branch is determined by an abrupt increase in the repetition rate reflected pulses, specify space branch connection by the presence of negative polarity pulse waveform, and place the end of the branch is determined by an abrupt decrease of the reflected pulse repetition frequency, determined by the tap length proximate the point of attachment and place the end of the branch.

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